The present invention is directed to a transport or conveying apparatus for small hardware items in a fluidized bed where an inclined gas-permeable base covers a plurality of gas supply chambers located on the lower side of the base.
Apparatus for the continuous heat treatment of granular material by a gas, in a sloping fluidized bed containing several gas supply chambers, has a material guiding flap at the inlet side and a baffle wall adjustable in height at the outlet side, as well as actuation means for regulating the gas supply, and is disclosed in DE-AS 21 01 143. In this apparatus a constant output is achieved using guidance and actuation means and a constant outlet temperature of the granules is attained by a constant gas temperature.
The gas inlet apertures of each gas feed or supply chamber are variable in cross-section by means of a perforated plate and an associated perforated slide.
The mechanical cross-sectional changes of the gap inlet apertures have disadvantageous effects. Based on the type of granular material used and on the temperature of the fluidized bed, disturbances can occur in the regulation means. Such disturbances can be caused by jamming of parts due to different heat expansions, by mechanical damage due to wear, or by contamination of the moving parts. Accurate adjustment of the cross-section of the gas inlet or feed apertures is no longer possible.